Scale Aviation Modeller International — February 2018

11’s run of 755 operational units

(852, including all bomb types

and trainers), which was actively

deployed from March 1945 right

to the end of the war in August.

A number of sub-contractors

were involved in the programme:

the core fuselage was fabricated by

Kanagawa, the wings and tail were

built by Fuji Hikoki, cast parts were

produced in Osaka and Hiroshima,

and sundry other fittings were

made in the Tokyo area. The final

assembly line was in Yokosuka.

An unsuccessful drop test flight

of the much modified Ohka Model

22 airframe occurred on 26 June

1945, with the employment of

two Type 4-1 Model 10 auxiliary

rockets in place of the intended

jet engine. An aborted second test

flight took place on 12 August 1945,

with the prototype jet engine,

which prematurely ignited before

separation from the mothership.

No definitive handling or flight

characteristics were obtained with

these two aborted test flights,

apart from the expectation of a

crucial 130 km range (from trial

engine runs and fuel consumption

calculations, if dropped from a

height of 4,000 m), an estimated

maximum speed of 514 km/h,

and a ceiling of 8,500 m.

The airframe of the Ohka Model

22 had an overall length of 6.88

m and a wingspan of 4.12 m. This

was longer and narrower than the

earlier version, and heavier, with an

all up operational weight of 2,510

kg. One of the most significant

revisions to the original Model 11

configuration was the reduction

of the 1,200 kg “Tekkou” armour-

piercing ammonal-filled warhead,

with a 600 kg one for the Model 22.

Without doubt, the most

significant advance on the early

Ohka had to be its propulsion,

a low-powered Campini-flow

Ishikawajima Tsu-11 thermo-jet

engine, consisting of a 110 hp

Hitachi GK4A Hatsukaze 11 (Ha-

11-11), four cylinder in-line engine,

driving the core single-stage

axial compressor. With a fuel tank

capacity of 290 litres, this was a

novel combined unit, producing a

thrust of about 200 kg, sufficient to

propel such an air-launched device.

Two protuberant air intakes

were located abaft the cockpit.

The single jet exhaust nozzle

extended quite far beyond the tail,

while the piston-engine exhaust

was located under the tail. These

prominent features were markedly

divergent from the original Okha

Model 11 rocket configuration.

It appears that only some

twenty experimental Tsu-11 jet

engines were ever produced before

the end of the war. Therefore, it

is presumed that a number of the

stated 35 “completed” airframes

were engineless, awaiting

their core propulsion unit.

THE MODEL

I obtained my example of the

Yokosuka MXY7 Ohka Model 22

(Kit No. BRP48002) direct from

Brengun in the Czech Republic,

for a total of £18.45 including

postage. It arrived in short order,

in more than adequate protective

package, with everything sound,

intact, and ready for my project.

This relatively small model,

in 1/48 scale, came in a rather

spacious end-opening box,

measuring 30 cm by 20 cm by

5 cm. It has nice top artwork of

an Ohka Model 22 on its ground

handling trailer, with the reverse

of the box providing a full painting

and decal application guide.

The principal sprue carries the

42 light buff plastic components

for this rudimentary craft and

My usual initial parts tree check quickly revealed that Brengun

had modelled a superb Ohka Model 22 companion to my earlier

Ohka Model 11 from Fine-Molds

As with their principal ‘special’ aircraft model, Brengun have committed a fair degree of care and

attention towards its ground handling trolley, a mini-model in its own right, a good uncomplicated

build which went together without any problem

The two core components involved nearing completion, all that is left is the union of these two

principal sub-assemblies in this dual build, ready for final painting

Because of the light tree attachment points and no

imperfections, preparation work was minimal allowing one to

commence a fuss-free build in short order

A weighted nose is absolutely essential in finally enabling this

craft to sit correctly on its trolley, here I called upon Dinsmores

super soft shot as the ideal medium. Interior and cockpit detail is

emphasised through some deft paint work.

78 • FEBRUARY 2018 • SCALE AVIATION MODELLER INTERNATIONAL

076-81-FEAT-Okha-0218.indd 78 12/01/2018 12:11